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Muscarinic Autoreceptors of Torpedo Electric Organ Are of the M 1 Subtype: Evidence by Radioligand Binding Using Selective Antagonists
Author(s) -
Green A. C.,
Dowdall M. J.
Publication year - 1992
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1992.tb09746.x
Subject(s) - pirenzepine , methoctramine , muscarinic acetylcholine receptor , autoreceptor , muscarinic acetylcholine receptor m2 , muscarinic acetylcholine receptor m3 , medicine , endocrinology , muscarinic acetylcholine receptor m1 , muscarinic acetylcholine receptor m4 , chemistry , radioligand , muscarinic acetylcholine receptor m5 , biology , receptor , antagonist
The presynaptic muscarinic autoreceptor of Torpedo marmorata electric organ has been characterised by radioligand binding studies using the subtype‐selective antagonists pirenzepine, (+)‐telenzepine, methoctramine, and AF‐DX 116. The presynaptic receptor had relatively high affinity for the M 1 antagonists pirenzepine and (+)‐telenzepine ( K i = 35 and 7 n M , respectively) and lower affinities for the M 2 antagonists AF‐DX 116 and methoctramine ( K i = 311 and 277 n M , respectively). Comparison of these binding data with those from an M 2 receptor (rat heart membranes) assayed under identical conditions and with data in the recent literature suggests that the Torpedo muscarinic autoreceptor has a pharmacology most similar to the M 1 pharmacological subtype of muscarinic acetylcholine receptor.